Flow control valve

ABSTRACT

A flow control valve is formed of valve body having a longitudinally extending bore containing a main spool axially, slidably positionable within the bore and arranged to be centered along its axis. A pair of slidable subsidiary spools is positioned within an axially extending passageway in the main spool with each of the spools being located on an opposite side of a transverse plane dividing the main spool in half. Each of the subsidiary spools has an axially extending passage which is divided by a partition into two chambers with a sharp-edged orifice in the partition affording communication between the two chambers. Openings through the valve body, the main and subsidiary spools afford fluid flow through the chambers in the subsidiary spools so that the fluid can be passed in either direction through the sharp-edged orifices in the partitions.

United States Patent [72] Inventor MasaoYoshino No. 26-8, l-Chome. Numabukuro, Nakano- Ku, Tokyo, Japan [21] AppLNo. 815,632 [22] Filed Apr. 14,1969 [45] Patented Jan. 12,1971

[541 now CONTROL VALVE 6 Claims, 6 Drawing Figs.

[52] U.S.Cl. 137/101, 137/111, 137/118 [51] 1nt.Cl. ..G05dll/00 [50] FieldofSearch 137/100, 101

[561 References Cited UNITED STATES PATENTS 2,386,291 10/1945 Browne 137/101 137/101 2,985,184 5/1961 Bowersetal.

3.113,581 12/1963 Presnell 3,347,254 10/1967 Comptonetal.

ABSTRACT: A flow control valve is formed of valve body having a longitudinally extending bore containing a main spool axially, slidably positionable within the bore and arranged to be centered along its axis. A pair of slidable subsidiary spools is positioned within an axially extending passageway in the main spool with each of the spools being located on an opposite side of a transverse plane dividing the main spool in half. Each of the subsidiary spools has an axially extending passage which is divided by a partition into two chambers with a sharp-edged orifice in the partition affording communication between the two chambers. ()penings through the valve body, the main and subsidiary spools afford fluid flow through the chambers in the subsidiary spools so that the fluid can be passed in either direction through the sharp-edged orifices in the partitions.

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4 2 58N PM 1 4' JFE P7D'D IT C6D.'D'7'A INVENTOR M9560 YOSHINO ATTORNEYS 1 FLOW CONTROL vALvE BACKGROUND or THE Invention The flow control valve provided by the invention disclosed in the specification of U.S. Pat.v No. 3,437,103 on which;the present invention is based serves alternatively as a flow-dividing and-a flow-combining'valvefor-synchronizing the operation of hydraulic devices by equalizing the flow of fluid to said hydraulic devices. The valve comprises a spool disposed in a longitudinally extending boreformed in a valve body, flow- SUMMARY or TI-IE Inven tion The present invention relatesto flow control valves in general. In particular, the invention deals with improvements ina flow-control valve adapted to serve alternatively as a flowdividing and aflow-combining valve for synchronizing the operation of hydraulic devices disclosed in thespecification of the aforesaid U.S. Pat. No. 3,437,103.

I have carried out further studies on the construction of the aforesaid fiow-control valveand succeeded in producing an improved flow-control valve of the type disclosed herein which has increased accuracy and precision in controlling the flow of a pressurized hydraulic fluid with minimized errors inadjusting the flow of the fluid througlitwo passages in the valve body connecting the hydraulic devices'to the sourceof. said fluid. The iinproved flow-controlnvalve is simple in construction and easy to manufacture; v

Accordingly, the object of the present invention is to provide a flow-control'valve having increased accuracy and precision in functioning alternatively as a flow-dividing and a flow combining valve which comprises a-valve body having alongitudinally extendingbore. therethrough, a longitudinally extending main spool positioned within saidlbore in said valve bodyfor sliding motion relative to th e valve body,'and a plurality of subsidiary spools positionedfin saidrnain spool in end to end relation on the leftfandright sides of the valve for sliding motion relative to eachother, each of said subsidiary spools being formed with a passage extending therethrough and'adapted to register with orie passageof each pairof two pairs of passages formed in said main spool, each of said subsidiary spools having a. partition wall; formed integrally therewithfor dividing each subsidiary spool into two fluid chambers, said partition wall having an annular sharp-edged. orifice formed therein for maintaining communication betweensaid two chambers in each subsidiary spool.

According to the present invention, there is provided a flow-control valve being adapted to serve alternatively asa flow-dividing and a flow-combining value for synchronizing the operation of hydraulic devices, co mprising a valve body having a longitudinally'extending bore therethrough, a longitudinally extending main spool slidably positioned with surface engagement within said bore in said valve body, a plurality of subsidiary spools positioned symmetrically in end to end relation on the left and right sides of the valvewithin said main spool longitudinally thereof for sliding motion relative to each other, spring means for urging said main spool from opposite ends thereof so as to accuratelyposition themain spool in the center-of the bore, and stop means mounted nearithe opposite:

in the other side wall thereof and offset in the longitudinal direction one on each' side of said first passage, said main spool having a first passage therethrough communicating with an intermediate passage in the main spool and arranged to register with the first passage in said valve body for flow therebetween. said main spool having two pairs of second passages extending therethrough offset in the longitudinal direction one pair on each side of the first passage through said valve body so that one passage-of each pair of said two pairs of second passages is adapted to index with one of said two second passages in said valve body. said subsidiary spools each having a passage therethrough adapted selectively to index with one passage of each pair of said two pairs of second passages in the main spool depending on the pressure of fluid flowing therein, said subsidiary spools each having a partition wall therein formed integrally with each said'subsidiary spool to provide two fluid chambers. said partition wall in each said subsidiary spool being formed with an annular sharp-edged orifice therethrough for maintaining communication between said two fluid chambers in each said subsidiary spool.

BRIEF DESCRIPTION OF THE Drawings Additional objects as well as features and advantages of the invention will become apparent from the description set forth valve embodying the present invention serving as a flow com bining valve; and

FIG. 6 is a diagram showing the flow of a hydraulic fluid through the flow control valve of this invention.

DESCRIPTION OF THE PREFERREDEmbodiments The construction of the flow-control valve according to the present invention will be explained \vithreference to FIGS; 4 and 5,. It is to be noted that the flow-control valve of this invention is characterized by the fact that'the elements making up the valve are arranged symmetrically on'the left and right sides of the valve and that the elements disposed on the right and left sides of the valve operate in exactly the same manner. The flow-control valve includes avalve body A which has'in the center a longitudinally extending bore for receiving therein a longitudinally extending main spool C for sliding motion. Two subsidiary spools Band D are disposed'iriend to end relation on the left and right sides of the valve in saidmain spool C for sliding motion relative to each other; A'k ey E'forrestricting the movement of the subsidiary spools D and D away from each other and a stop ring F for firmly fixingsaid key E are mounted near each of the opposite surfaces of themain spool C.

A-cover B is attached to each of the opposite ends'of'thevalve body A. An O-ringJ is mounted insaid cover B for providing a seal to the valve body- A and another O rin'gJ is mounted in a stopper H to preventleakage of hydraulic fluidthrough the stopper I-l. Also mounted in each said cover 8- is a main spool Chas a partition wall'D or D formed integrally partition walls D and D has an annular sharp-edged orifice M or N formed therein. The subsidiary spools D and D are adapted to move in sliding motion in the main spool C in response to a resistance to a fluid flow offered by the orifices M and N.

The valve body A has openings P for mounting the flowcontrol valve to hydraulic devices. Set bolts K and lock bolts L are used for clamping the covers B to the valve body A.

Operation of the flow-control valve constructed as aforementioned will now be explained. FIG. 4 illustrates the flowcontrol valve serving as a flow-dividing valve as indicated by upwardly directed arrows showing the direction of fluid flow in the diagram of FIG. 6. FIG. 5 illustrates the flow-control valve serving as a flow combining valve as indicated by downwardly directed arrows showing the direction of fluid flow in the diagram of FIG. 6.

The flow of a hydraulic fluid introduced through a port 1 (alternatively serving as an inlet and an outlet port) formed in the valve body A into an intermediate passage 6 in the main spool C is divided into streams which flow into the subsidiary spools D and D' on the left and right hand of the valve body respectively. The stream of hydraulic fluid introduced into each of the subsidiary spools D and D passes through the annular sharp-edged orifice M or N into a fluid chamber 7 or 7' which is gradually filled with the hydraulic fluid. As the fluid passes through the annular sharp-edged orifice M or N, the resistance offered by the orifices to the fluid flow causes the subsidiary spools D and D to move away from each other till they come into engagement with the keys E for restricting the movement of the subsidiary spools. As the quantity of hydraulic fluid in the subsidiary spools increases, the fluid flows through the passages 4 and 4' in the subsidiary spools to be discharged through the ports 2 and 3 in the valve body to provide power for performing hydraulic operations.

In entering the liquid fluid chambers 7 and 7 from the intermediate passage 6, the fluid flows are subjected to the resistance offered by the orifices M and N respectively, and the subsidiary spools D and D are moved away from each other toward the right and left ends of the valve by this resistance. With the subsidiary spools in the outer positions, the passages 8 and 8 in the subsidiary spools D and D index with the passages 4 and 4' in the main spool C respectively. Assuming that the pressures in the ports 2 and 3 are 100 leg/cm. and 60 kgJcm? respectively, the main spool C will move to the right and the passage 4 will have a smaller degree of opening that the passage 4. The main spool C will continue to move to the right till the pressures in the fluid chambers 7 and 7' become equal to each other. With the pressures in the fluid chambers 7 and 7' balancing, the difference in pressure between the forward end and the rearward end of the annular sharp-edged orifice M becomes equal to the difference in pressure between the forward end and the rearward end of the annular sharpedged orifice N. If the two orifices M and N are identical in area, the quantities of hydraulic fluid distributed to the chambers on the left hand and right hand of the orifice M respectively will be equal to the quantities of hydraulic fluid distributed to the chambers on the left hand and right hand of the orifice N respectively. If there is a variation in area between the orifices M and N, the ratio of the quantities of hydraulic fluid distributed to the chambers on the left hand and right hand of the orifice M will vary from the ratio of the quantities of hydraulic fluid distributed to the chambers on the left hand and right hand of the orifice N. Assuming that the pressure in the ports12 and 3 are 30 kgJcm. and 80 kg./cm. respectively, the main spool C will move toward the left till the pressures in the fluid chambers 7 and 7 are equalized and distribution of hydraulicifluid is carried out in the same manner as aforesaid.

FIG. 5 hows the flow-control valve of this invention serving as a flow-combining valve. If the hydraulic fluid introduced into the port 2 and the hydraulic fluid introduced into the port 3 are under different pressures, the two flows of hydraulic fluid will move through the passages 5 and 5 in the main spool C and thei passages 8 and 8 in the subsidiary spools D and D into the fluid chambers 7 and 7 respectively. The hydraulic fluid in the fluid chambers 7 and 7 will pass through the annular sharp-edged orifices M and N and gather at the intermediate passage 6 to be discharged through the outlet port 1.

Assuming that the pressures in the ports 2 and 3 are 50 kg/cm. and 30 ltg./cm. respectively. the hydraulic fluid introduced through the port 2 and the passage 5 into the fluid chamber 7 in the subsidiary spool D will have a pressure of 50 kg./cm. while the hydraulic fluid introduced through the port 3 and the passage 5' into the fluid chamber 7 will have a pressure of 30 kg./cm.". Due to this differential pressure in the fluid chambers, the main spool C will move to the right. The rightward movement of the main spool C gradually reduces the degree of opening of the passage 5 in the subsidiary spool D and increases the difference in pressure between the port 2 and the liquid chamber 7. This results in a reduction in the pressure of fluid in the fluid chamber 7. When the pressure of fluid in the fluid chamber 7 reaches 30 kg./cm. the difference in pressure between the forward end and the rearward end of the annular sharp-edged orifice M becomes equal to the difference in pressure between the forward end and the rearward end of the annular sharp-edged orifice N. Accordingly, the quantity of hydraulic fluid combined in the valve can be maintained constant depending on the ratio of openings between the annular sharp-edged orifices M and N.

When the pressure of hydraulic fluid introduced into the fluid chamber 7 through the port 2 is lower than the pressure of hydraulic fluid introduced into the fluid chamber 7 through the port 3, the main spool C will move to the left. The rightward and leftward movements of the main spool C are alternately repeated rapidly to bring the main spool in the nor mal position.

The flow-control valve embodying the present invention offers many technical advantages over flow-control valves of the prior art. The provision of the annular sharp-edged orifices in the subsidiary spools permit to effect dividing of a flow of hydraulic fluid and combining of flows of hydraulic fluid at increased accuracy and precision. The flow-control valve of this invention makes it possible to synchronize the operation of hydraulic devices at high efficiency. The use of the annular sharp-edged orifices is advantageous and can achieve better results in functioning as a flow dividing and a flow combining valve, particularly from the point of view of temperature.

Main spools of the prior art have hitherto consisted of two parts connected together as a unit. Since it is impossible to impart precision finishes of equal degree to the two parts, the main spool of this invention is formed in one piece because it is essential that the right-hand portion and the left-hand portion of the valve have the same diameter. The use of the main spool formed in one piece has made it possible to produce the flow control valve of this invention.

Advantages of the annular sharp-edged orifice will be explained. A reduction in pressure AP can be expressed by the following formula:

AP due to throttling is generally given by AP=K 9- even if the flow rate remains constant. The change in temperature K is far smaller when the annular sharp-edged orifice that the flow control valve using the orifices has better tem-- 'perature characteristics than the flow control valve relying on throttling. g o a .l. A flow-control valve adapted for use as a flow-dividing and flow-combining valve in sychronizing the operation of hydraulic devices, comprising a valve body having a longitudinally extending bore therethrough,a main spool in coaxial relationship with and slideablypositionable within said bore, said main spool having an axially extending passageway therethrough. a pair of axially extending subsidiary spools slideably positioned within the passageway in said main spool with each of said subsidiary spools being positioned on the opposite side of a plane transversly bisecting bore in said valve body, means for centrally positioning said main spool in the longitudinal direction of said bore, means for limiting the extent of movement of said subsidiary spools in the longitudinal direction within the passageway in said main spool, said valve body having a first opening therethrough at approximately the center point of its longitudinal direction, said valve body having a pair of second openings therethrough each spaced on an opposite side of the first opening and being positioned between the first opening and the end of said valve body, said main spool having a first opening in said valve body and the passageway through said main spool, said main spool having two pair of second openings therethrough with each pair being positioned in the longitudinal direction on an opposite side of the first opening through the said main spool, each pair of second openings in said main spool being offset from one another in the longitudinal direction so that only one opening of each pair of the second openings in saidmain spool is in register with the second opening in said valve body for affording flow therethrough, each said subsidiary spool having a passageway therethrough and an opening therein arranged to register with one of the second openings in said main spool for affording a flow path from the passageway within said subsidiary spool to the second opening in said valve body. and a partition extending transversly across the passageway in each of said subsidiary spools and dividing the passageway into two separate chambers, said partition having a sharp edged orifice therethrough for affording communication between the two chambers within the passageways in said subsidiary spools.

2. A flow-control valve. asset forth in claim 1. wherein the bore through said valve body being open at its opposite ends. a said means for centrally positioning said main spool includes a cover secured to said valve body at each of its opposite ends for sealing the ends of the bore therethrough.

3. A flow-control valve, as set forth in claim 2. wherein said means for centrally positioning said main spool in the longitudinal direction of said bore further comprises a spring member located at each end of said bore and being supported against said cover and extending axially into the bore for centering said main spool therein.

4. A flow-control valve, as set forth in claim 3. wherein said means for limiting the extent of the movement of said subsidi ary spools comprising a key member extending across each end of said bore in said valve body adjacent said covers and a stop ring at each end of said bore for securing each said key in position whereby the axial movement of said subsidiary spools are limited at the opposite ends of said bore by said keys and stop rings.

5. A flow-control valve. as set forth in claim 1. wherein said second openings in said valve body being located in diametrically opposite sides thereof front said first opening.

6. A flow-control valve. as set forth in claim I. wherein said partition being located with the passageway in said subsidiary spools between the tirst opening through said main spool and the openings through said subsidiary spool. 

1. A flow-control valve adapted for use as a flow-dividing and flow-combining valve in sychronizing the operation of hydraulic devices, comprising a valve body having a longitudinally extending bore therethrough, a main spool in coaxial relationship with and slideably positionable within said bore, said main spool having an axially extending passageway therethrough, a pair of axially extending subsidiary spools slideably positioned within the passageway in said main spool with each of said subsidiary spools being positioned on the opposite side of a plane transversly bisecting bore in said valve body, means for centrally positioning said main spool in the longitudinal direction of said bore, means for limiting the extent of movement of said subsidiary spools in the longitudinal direction within the passageway in said main spool, said valve body having a first opening therethrough at approximately the center point of its longitudinal direction, said valve body having a pair of second openings therethrough each spaced on an opposite side of the first opening and being positioned between the first opening and the end of said valve body, said main spool having a first opening in said valve body and the passageway through said main spool, said main spool having two pair of second openings therethrough with each pair being positioned in the longitudinal direction on an opposite side of the first opening through the said main spool, each pair of second openings in said main spool being offset from one another in the longitudinal direction so that only one opening of each pair of the second openings in said main spool is in register with the second opening in said valve body for affording flow therethrough, each said subsidiary spool having a passageway therethrough and an opening therein arranged to register with one of the second oPenings in said main spool for affording a flow path from the passageway within said subsidiary spool to the second opening in said valve body, and a partition extending transversly across the passageway in each of said subsidiary spools and dividing the passageway into two separate chambers, said partition having a sharp edged orifice therethrough for affording communication between the two chambers within the passageways in said subsidiary spools.
 2. A flow-control valve, as set forth in claim 1, wherein the bore through said valve body being open at its opposite ends, a said means for centrally positioning said main spool includes a cover secured to said valve body at each of its opposite ends for sealing the ends of the bore therethrough.
 3. A flow-control valve, as set forth in claim 2, wherein said means for centrally positioning said main spool in the longitudinal direction of said bore further comprises a spring member located at each end of said bore and being supported against said cover and extending axially into the bore for centering said main spool therein.
 4. A flow-control valve, as set forth in claim 3, wherein said means for limiting the extent of the movement of said subsidiary spools comprising a key member extending across each end of said bore in said valve body adjacent said covers and a stop ring at each end of said bore for securing each said key in position whereby the axial movement of said subsidiary spools are limited at the opposite ends of said bore by said keys and stop rings.
 5. A flow-control valve, as set forth in claim 1, wherein said second openings in said valve body being located in diametrically opposite sides thereof from said first opening.
 6. A flow-control valve, as set forth in claim 1, wherein said partition being located with the passageway in said subsidiary spools between the first opening through said main spool and the openings through said subsidiary spool. 